Field of the Invention
The present disclosure relates to a fluid intake/discharge valve body used in the intake of a cryogenic liquefied gas into a cylinder liner and the discharge of the cryogenic liquefied gas with a piston, a reciprocating pump that employs the valve body, and a fuel gas supply device that employs the reciprocating pump.
Background Information
Conventionally, there are many diesel engines that operate with a natural gas generated by vaporizing a liquefied natural gas (hereinafter, referred as “LNG”) as a fuel. However, recently, various high-pressure gas injection two-stroke low-speed diesel engines have been provided, in order to improve emission performance of main engine for environment in a current two-stroke low-speed oil burning diesel engine. Accordingly, among diesel engines, a high-pressure gas injection two-stroke low-speed diesel engine is needed that has high thermal efficiency and high engine output. In particular, there is a need for an application to a marine vessel, etc.
For example, a gas fuel supply device for a natural gas or the like that is applied to a main engine or a generator-driven engine of a marine vessel, and a device that highly pressurizes a liquefied gas fuel via a reciprocating pump that may be easily disposed in a gas hazard area, are known (see, JP-A 2012-177333, hereinafter referred to as “Patent Literature 1”).
The device includes: a reciprocating pump driven by a hydraulic motor, the reciprocating pump configured to raise pressure of the liquefied gas that has been introduced up to a predetermined pressure, and to discharge the liquefied gas; a hydraulic pump unit configured to supply hydraulic pressure for driving the hydraulic motor from a variable-capacity hydraulic pump that is driven by an electric motor; a heating device configured to heat and gasify liquefied gas supplied from the reciprocating pump after the pressure has been increased; and a controller configured to adjust a rotational velocity of the hydraulic motor, and to maintain a constant gas fuel input/output pressure of the heating device. In other words, a hydraulic pump unit positioned outside a gas hazard area is configured to supply hydraulic pressure for driving the hydraulic motor from a variable-capacity hydraulic pump that is driven by an electric motor to a hydraulic motor positioned in a gas hazard area, and to drive the reciprocating pump using hydraulic pressure, such that the pressure of the liquefied gas is raised to a predetermined pressure and the liquefied gas is discharged.
Moreover, a cryogenic liquid piston pump that has been designed for a high operating pressure is also known as an example of a reciprocating pump (see, JP-A 2012-2224, hereinafter referred to as “Patent Literature 2”). In the piston pump, a valve head includes: a cavity that corresponds to a piston distal end having an outlet opening; and an exhaust valve is adjacent to the outlet opening. The exhaust valve is positioned so as to be inserted into a cylinder head. The piston distal end configured to pass through a region of the cavity in a case where a piston pump operation is being maximized. Accordingly, the piston distal end is configured so as to tightly fit into the cavity of the valve head. A low temperature medium is always completely mechanically exhausted from the valve head during each piston pump operation via a complete insertion of the piston distal end into the cavity region during a maximum piston operation. The exhaust valve is directly adjacent to the outlet opening of the valve head, and the exhaust valve is positioned so as to be inserted into a sealed pressure pipe. Accordingly, a cavity within a pump operation chamber in which the residual low temperature medium may remain is lacking, and functional disorder from a residual medium is significantly decreased.